The present invention relates to an optical coupler for use with optical fiber communication systems or the like. More particularly, the present invention is concerned with an optical coupler having a plurality of input ports and a plurality of output ports and capable of guiding light incident on a desired one of the input ports to all of the output ports.
With the recent improvement in the quality of optical semiconductor elements and optical fibers, optical communications using optical fibers have made rapid progress in practical usability. The usefulness of such a type of communication has been found in connection with data transmission systems in particular. Where optical communication is applied to a data transmission system, one of the indispensable devices will be an optical coupler which can deliver common data to multiple local stations at the same time.
An optical coupler employing waveguide passages or guide channels formed on a substrate has been proposed by Takado et al., as disclosed in the 1979 National Convention Record of the Institute of Electronics and Communication Engineers of Japan. As shown in FIG. 1, the optical coupler has guide channels which extend from a plurality of input ports 101-106 to a plurality of output ports 107-112 by way of an intermediate mixing section 113. The guide channels are formed on a substrate 114 using polymer material. Light incident on any one of the input ports 101-106 can propagate to all the output ports 107-112 via the mixing region 113. However, since optical fibers must be connected to the optical coupler in practice, the prior art optical coupler requires troublesome manipulation for accurately positioning each optical fiber before fixing it to the optical coupler.